This Sunday's readings present a most basic human value: hospitality. The two sisters, Martha and Mary, welcome Jesus into their home. (Lk 10:38-42) Similarly, Abraham receives three mysterious visitors. (Gen. 18:1-10) He bathes their feet, prepares food and a place for them to rest. The three are actually the One God. On account of his hospitality, He gives Abraham what he most desired. His wife Sarah, in spite of her advanced age, conceives a child and within a year gives birth to a son. Because of their incredulity - and sheer joy - they name the child, Isaac, from the Hebrew word yishaq, meaning, "laughed."

Hospitality is not only an important personal virtue. It has great social implications - which are being severely tested in our society. The virtue has two parts: Because a visitor is vulnerable, it means to care for him, and to the degree possible, provide protection. But more profoundly, hospitality involves recognizing the stranger as a person - a subject, not an object.

These two principles of hospitality relate to something happening in our country, which must be a grave concern for each of us. Sooner or later it will affect you and me personally. I am referring to the controversy over stem cell research. This Sunday I would like reflect on this issue in light of our faith - and what we have heard in our Bible readings.

First, let me clear up a misunderstanding. The Catholic Church is not against stem cell research. It is possible to obtain stem cells from adult bone marrow or umbilical cords and to use them in research. There is no moral problem with that. In fact the Church encourages this research. Many patients have already benefited from treatments involving adult stem cells. Their use can be compared to a skin graft or kidney transplant. They can save or improve one human life without destroying another. Research using adult stem cells deserves our support.

The problem arises because some want to use human embryos as a source of totipotent stem cells, that is, they can develop into any body tissues - hearts, kidneys, brains, etc. By extracting those cells, they will kill the embryos. Why is this wrong? To answer we must first ask, What is a human embryo?

Let me give an illustration. About 2000 years ago a young Jewish girl had inside herself a tiny embryo. Since it was a male embryo, we don't need to say "it" but "he." Possessing totipotent stem cells, he developed into a blastocyst, then a fetus, finally nine months later was born. We celebrate his birthday on December 25. I think you know who I mean. The point is Jesus began his human existence the same way you and I do, as a microscopic embryo. His mother Mary welcomed Jesus. She cared for him and protected him like every good mother does, because she wanted the best for her child.

However, some mothers and fathers in our country have not been so protective. We have a terrible situation: It is estimated there are about 100,000 frozen embryos in the United States. Each one has mother and father. They probably did not think through the consequences when they allowed their offspring to be conceived that way - apart from the mother's protection and nourishment, in petri dishes. Many have become "orphans," that is, their parents do not recognize or want them. Because the orphaned embryos will likely be disposed of, some are saying we should use them for research.

There was a similar situation during World War II. Certain classes of people - Gypsies, Slavs, Jews - were judged sub-human or non-human. Since they were destined for extermination, doctors decided to use a few of them for medical experiments. After the War those doctors were universally condemned. Scientists with clear moral consciences said the research, even though it contained discoveries that could be beneficial, should be destroyed. We cannot use research that is gained in such immoral and inhuman ways, using other human beings as objects, without their consent.

I know some good people are genuinely confused. When they see a human embryo under a microscope, it does not have arms or legs so they are unsure if it is really human. I can only say that when it comes to something so important as a human life, it is better to err on the side of caution.

If a deer hunter looks across a field and sees a bush move, he might be pretty certain it is a deer. Still, it could be another hunter or even a child. Would he shoot? Even if the chance were only one in a thousand that it was a child, would he run the risk just for a freezer of venison? The very fact one entertains doubts about the humanity of an embryo means one should not chance killing a tiny human - no matter how great the potential benefit.

We do not utilize human life, we welcome it. The Gospel principles of hospitality are illustrated by the two sisters. Martha, a busy person, takes care of Jesus' physical needs. To provide a caring, protective environment is so important. Thank God for our Marthas! But Mary did something more basic - what Jesus calls the "only thing needed" because listening, treating the other as a human subject, opens one to everything of value. When the subject is Jesus, that is true in an absolute sense. For that reason he says, "Mary has chosen the better part and it will not be taken from her." (Lk 10:42)